1. Field of the Invention
The present invention relates generally to the field of bookbinding, and more particularly, to a bookbinding structure and method that may be used with a wrap-around book cover.
2. Description of Related Art
Bookbinding systems utilizing binder strips are well known. Binder strips are used to bind pages together to form a book in which the binder strip forms the spine of the book. Binder strips which use a heat activated adhesives of low and high viscosity are used to bind a stack of sheets using heat and pressure which are applied to the strip and stack using a special purpose binding machine.
U.S. Pat. No. 4,496,617, the contents of which are hereby fully incorporated herein by reference, describes such a binding strip. The strips include an elongated paper substrate and an adhesive matrix disposed on the substrate. The matrix includes a central adhesive band which is heat activated and which has a relatively low viscosity when activated and a pair of outer adhesive bands. The outer bands are also heat activated, but are of a relatively high viscosity. The central adhesive band functions to secure the edges of the pages to be bound together and to the substrate and the outer bands function to secure the front and back cover pages to the substrate.
Such prior art binder strips are, however, not suitable for some applications due to the appearance of books bound by such strips. The spines of books bound by the conventional binder strips are often devoid of any printed information because the binder strips require specialized equipment for printing on the strip. Moreover, it is sometimes desirable to have a uniform cover having a continuous design from the front cover to the back cover, frequently including the spine. A conventional binder strip cannot provide a bound book having a cover with such a continuous design.
Another prior art bookbinding system, such as disclosed in U.S. Pat. No. 4,289,330, utilizes a continuous cover structure that forms the front and rear covers of the bound book together with the spine. A heat activated adhesive is deposited on the inside of the cover structure to secure the individual pages together. A significant disadvantage of such continuous cover structures is that many printing processes utilize heat sensitive inks which would be adversely affected by the heat applied to the cover structure during binding. Thus, it would not be possible to print on the cover structure using such popular printing processes. Furthermore, the presence of the adhesive on the cover structure can be bulky thereby making printing difficult using some types of printers. In addition, somewhat specialized equipment is needed to carry out the binding process.
The present invention overcomes the shortcomings of the above-described prior art. It is possible to carry out the binding process using the same machine used to bind books using conventional binder strips of the type disclosed in U.S. Pat. No. 4,496,617. Some of the embodiments of the invention permit the front and rear covers and the spine of the final bound book to be printed prior to binding using a wide variety of printing techniques including techniques employing heat sensitive inks. These and other advantages of the present invention will become apparent to those skilled in the art upon a reading of the following Detailed Description of the Invention.
A bookbinding structure and method are disclosed. The structure includes an elongated substrate having a length that is equal to the length of the stack of pages to be bound. An adhesive matrix is included which is supported by the substrate and which includes a pair of outer adhesive bands extending along a longitudinal axis of the substrate and a central adhesive band intermediate the outer adhesive bands. The outer adhesive bands have a viscosity when activated which is greater than the viscosity of the central band.
The bookbinding structure further includes an adhesive layer supported by the substrate and having a first surface facing a first surface of the adhesive matrix. Means for exposing the second surface of the adhesive layer, opposite the first surface, is included which permits a cover assembly to become attached to the bookbinding structure by way of the adhesive layer after the pages have been bound.
In one embodiment, the adhesive layer is a pressure activated layer disposed on the substrate surface opposite the substrate surface on which the adhesive matrix is mounted. The means for exposing includes a release liner disposed over the pressure activated adhesive. The release line is removed after the stack has been bound by the adhesive matrix thereby exposing the pressure activated adhesive so that the pressure activated adhesive can be used to attach a cover assembly to the stack.
In a further embodiment, the adhesive layer is a solvent activated layer disposed on one surface of the substrate opposite a substrate surface on which the adhesive matrix is mounted. After the stack has been bound with the adhesive matrix, a solvent is applied to the adhesive layer so the solvent activated adhesive can be used to attach the cover assembly to the stack.
In a still further embodiment, the adhesive layer is a heat activated layer disposed intermediate the adhesive matrix and the substrate. After the stack has been bound with the adhesive matrix, the cover assembly is positioned over the adhesive layer and heat is reapplied to the adhesive layer through the cover assembly thereby activating the adhesive layer so that the cover assembly will be secured to the bound stack.